(a) Field of the Invention
The present invention relates to a communication method and apparatus for preventing communication link failure in a millimeter band communication system.
(b) Description of the Related Art
A super high frequency (SHF) band is about 3˜30 GHz and an extremely high frequency (EHF) band is about 30˜300 GHz. The EHF band includes electromagnetic waves which have a wavelength of a millimeter unit. The frequency of the SHF/EHF band has different characteristics from those of the frequency of the band used in the prior mobile communication.
The SHF/EHF band has merits as follows. The size of a wavelength is very small, and thereby it is possible to miniaturize the antenna for transmitting/receiving and a device, and also to reduce weight thereof. In addition, a wider channel bandwidth than the frequency bandwidth of the prior communication is provided, and thereby the amount of information transferred can be significantly increased. Accordingly, the SHF/EHF band is likely to be used as a communication frequency of the next generation mobile communication system such as a wideband code division multiple access (WCDMA), a long term evolution (LTE), and others.
On the other hand, the SHF/EHF band has propagation characteristics of strong straightness, which may increase a frequency reuse rate while being subjected to severe interference by obstacles, and may be sensitive to the atmospheric environment such that path loss of signals increases and it may be somewhat unsuitable for long distance communication.
Due to the propagation characteristics of the SHF/EHF band, unlike the prior mobile communication system such as the WCDMA, the LTE, and others, there is no multi-path channel caused by reflection at an independent path. Therefore, communication is impossible if line-of-sight (LOS) is not ensured.
In a mobile communication system, channels are often changed due to instantaneous movement or motion of things around a user (a receiving terminal) or the users own instantaneous movement or motion, and thereby the LOS is not always ensured. Accordingly, communication link failure often occurs.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.